The genetic relationship between people originating from each Family Loom was lateral rather than direct, meaning that people from the same Loom were "cousins" of each other. Many Gallifreyans were loomed as "full-grown adults", albeit ones that began child-like and had to mature mentally. (PROSE: Lungbarrow)

Looms also kept a tally of all the people they birthed, and could normally indicate how old each of its "offspring" was and how many regenerations each had gone through. Data from all the Family Looms on Gallifrey was sent to the Bureau of Loomographic Records, which served as a central repository of genetic information.

Each Great House had a specified number of cousins which could exist in the Family at any given time. The House of Lungbarrow, for example, was allotted forty-five cousins. When a member of a Family died for the final time, the Loom would weave a new cousin into the Family. Cases did exist when an additional cousin was illegally woven, such as the Doctor's cousin Owis, but these were extremely rare. (PROSE: Lungbarrow)

I can remember waiting to be born... It was like being all strung out. All unravelled inside the Loom. I was spread really thin... I couldn't think. Not put thoughts together... But I knew where I was and what was happening. I couldn't wait to get out. And then I was born. My lungs nearly burst. The first rush of air was so cold..."The Doctor [src]

However, there were instances of womb-born children during the period where Looms were in use. Rassilon passed a decree that "only the Loom-born shall inherit the Legacy of Rassilon", and enforced this decree by wiping out the womb-born. (PROSE: Cold Fusion) In the Doctor's time, Time Lords born of a Loom were seen as "high born." (PROSE: Celestial Intervention — A Gallifreyan Noir) However, some womb-born survived this persecution and hid among the general population for hundreds of centuries. (PROSE: The Infinity Doctors)

When Rassilon and the Cybermen conquered Gallifrey, they used Looms to trap captured Time Lords in a state of perpetual regeneration, where the Looms could harvest the energy created. The Cybermen later linked it to the Cyberiad and the Eye of Harmony, where they planned to alter history. The Twelfth Doctor and Rassilon countered this plan by using the energy to regenerate the universe and return history to normal. (COMIC: Supremacy of the Cybermen)

Like many ideas and concepts in Doctor Who, this has not been referenced on-screen, and can be seen to contradict other sources. There have been many statements by the Doctor and others referring to him being a "boy" or showing the Doctor and other Time Lords as children.

Steven Moffat said that it was "reasonable to assume that Time Lords [met] and marr[ied] and mate[d] in much the same way" humans did. He acknowledged "some highly inventive material in the Virgin New Adventures books contradicting this" and described the New Adventures as "a separate (and equally valid) continuity" to the modern BBC Wales TV series.[1] When asked if series 11 would confirm the existence of Looms, Chris Chibnall said he had not read Lungbarrow.[2]

Lance Parkin's short story Executive Action, published in the charity anthologyWalking in Eternity, contextualized the conflict between Loomed and Womb-Born seen in Cold Fusion and referenced in The Infinity Doctors. Loomed Gallifreyans were said to be considered "pale imitations" to the Womb-Born, with considerably weaker mental powers, suggesting that Rassilon instigated the forced social change to ensure that no Time Lord could become more powerful than him.